Soil remediation is a growing demand and is accompanied by major challenges in terms of public health and environmental protection.
When soluble pollutants are released following contact with water there is a significant potential risk of environmental pollution during short-term or final storage, or when contaminated soil is reused.
To limit this risk, the landfilling of contaminated soil requires first that the hazard class of the soil be lowered.
Lowering the hazard class can also allow the treated soil to be reused, for example in road sub-bases or in embankments.
Lowering the hazard class of contaminated soils is equivalent to lowering the level of water-leachable pollutants.
Hydraulic binders are already used to treat contaminated waste or soil. Anionic pollutants, such as sulfates or heavy metals, present in contaminated soil can be trapped during the hydration process of a hydraulic binder mixed with the soil to be treated and with water. These elements can be trapped in hydrates of type C-S-H (calcium-silicate-hydrate) or sulfoaluminates of type ettringite or calcium monosulfoaluminate. Some elements can also be stabilized as hydroxides.
In application EP 0 588 689, Kerneos describes the use of binders containing active alumina to treat municipal waste incineration residues. The main mineralogical phases of these aluminous cements are CA or CA and C12A7 or C3A and C12A7.
In these binders, sulfate binding is based on the formation of calcium sulfoaluminate hydrate, mainly ettringite. However, these binders themselves provide sulfates or their reactivity remains limited, which limits the rapid and significant binding of sulfate ions.